1. Field of the Invention
The present invention relates to a gas distribution plate and a substrate treating apparatus including the same.
2. Background of the Related Art
In general, semiconductor devices, display devices, solar cells, and the like are manufactured through various processes for substrates. For example, a thin film deposition process and a photolithography process and an etching process are performed several times to form circuit patterns on the substrate, and additional processes such as a cleaning process, an attaching process, a cutting process and the like are performed. Among these processes, the deposition process and the etching process are performed in a chamber type substrate treating apparatus. To do this, a reaction gas is supplied onto the substrate through a gas distribution plate of the apparatus, thus a thin film is deposited or etched on the substrate.
FIG. 1 is a cross-sectional view illustrating a substrate treating apparatus according to the related art, and FIG. 2 is a cross-sectional view illustrating deformation of a gas distribution plate according to the related art.
Referring to FIG. 1, a PECVD (plasma enhanced chemical vapor deposition) apparatus is generally used as the substrate treating apparatus 10. The substrate treating apparatus 10 includes a chamber 11 including a chamber lid 12 to provide a reaction space E therein. A substrate 2 is placed on a substrate placing plate 14, and a heater 28 is installed in the substrate placing plate 14. A gas distribution plate 20 injects a reaction gas toward the substrate placing plate 14. An edge frame 26 is fitted into an inner wall of the chamber 11 and functions to prevent deposition of thin film at peripheral regions of the substrate 2. A gas supply pipe 24 supplies the reaction gas to the gas distribution plate 20. An exhaust port 22 functions to exhaust the reaction gas of the reaction space E and to adjust vacuum of the reaction space E.
The chamber lid 12 connected to a RF (radio frequency) voltage source 13, and the substrate placing plate 14 connected to a ground terminal function as an upper electrode and a lower electrode, respectively. Accordingly, the chamber lid 12 and the substrate placing plate 14 function to activate the reaction gas when the reaction gas flows into the reaction space E.
The gas distribution plate 20 includes a plurality of injection holes 18. The gas distribution plate 20 is coupled with the chamber lid 12, and an accommodating space is formed between the gas distribution plate 20 and the chamber lid 12 and functions to accommodate the reaction gas supplied from the gas supply pipe 24. The substrate placing plate 14 moves down to load/unload the substrate 2, and moves up to form or etch a thin film on the substrate 2. In other words, the substrate placing plate 14 is configured such that it moves up and down.
The edge frame 26 is fixed into the inner wall of the chamber 11. The edge frame 26 shields the peripheral regions of the substrate 2 when the substrate placing plate 14 moves up, thus formation of thin film at the peripheral regions of the substrate 2 is prevented.
The gas supply pipe 24 is installed such that it passes through a middle portion of the chamber lid 12. A baffle (not shown) is installed at a location of the accommodating space corresponding to the gas supply pipe 24, and functions to uniformly distribute the reaction gas from the gas supply pipe 24. The exhaust port 22 is coupled with a vacuum pump (not shown) so that the reaction gas of the reaction space E is exhausted or vacuum of the reaction space E is adjusted.
The thin film deposited on the substrate 2 is required to have a uniform thickness and property all over the substrate 2. The uniform thickness and property is influenced by uniform supply of the reaction gas onto the substrate 2 and uniformity of plasma generated between the gas distribution plate 20 and the substrate placing plate 14. A dominant one out of factors influencing the uniform supply of the reaction gas and the uniformity of plasma is uniformity of distance between the gas distribution plate 20 and the substrate placing plate 14. In other words, when the distance between the gas distribution plate 20 and the substrate placing plate 14 is entirely uniform, uniformity of the thin film on the substrate 2 is obtained.
The gas distribution plate 20 before the process of depositing the thin film on the substrate 2 has a status in parallel with the substrate placing plate 14, as shown in FIG. 1. However, when the process of depositing the thin film on the substrate 2 is performed, a temperature of the reaction space E is required to increase to a predetermined temperature for decomposition and reaction of the reaction gas. Because of the temperature increase, the gas distribution plate 20 attached to the chamber lid 12 is expanded. When the gas distribution plate 20 is expanded, the gas distribution plate 20 weighs down under the weight of the gas distribution plate 20, as shown in FIG. 2. Accordingly, distance between the gas distribution plate 20 and the substrate placing plate 14 decrease from edge to middle. In other words, the distance Dedg at edge is more than the distance Dcen at middle.
Furthermore, as the substrate 2 and the gas distribution plate 20 increase in size for a large-sized display device or solar cell, the weigh-down deformation of the gas distribution plate 20 becomes more serious. Accordingly, density of the reaction gas supplied onto the substrate 2 and density of plasma between the gas distribution plate 20 and the substrate placing plate 14 are not uniform, thus deposition uniformity of the thin film on the substrate 2 is difficult to obtain. Further, when the thin film on the substrate 2 is etched, etching uniformity is difficult to obtain. Therefore, uniformity of the thin film is degraded and production efficiency is reduced.